Original blueprints for Teesside's best known landmark are being painstakingly repaired by hand, to preserve them for future generations.
The bridge has been granted Grade II Listed Building status
Middlesbrough's Transporter Bridge has been a symbol of the area since it was opened in 1911.
Now the prints, which detail everything from the overall plans to individual nuts and bolts, are being restored at Teesside Archives.
Once this is complete they can be copied and viewed by the public.
Helen Kendal, the project leader, said a lot of them had been badly stored through the years.
She said: "They are rolled up, many of them are creased, torn, with pieces missing and they are also quite dirty so a lot of work needs doing.
"I'm going to be surface cleaning them to get some of the dirt off and then I'll be gently humidifying them to flatten them.
"Any tears will be repaired and missing pieces filled in, then they will be put into a polyester sleeve, rolled up and stored in the dark because they are sensitive to light."
The plans will then be digitalised, and some copies used in a conservation report produced by the council.
The bridge is 850ft long and 225ft high at the tallest point, and is believed to be the largest working bridge of its kind in the world.
It also a bit of a film star, having featured in the film Billy Elliot, and attracted national attention when it was "dismantled" during an episode of Auf Wiedersehn Pet.